Sleep apnea reduces growth hormone secretion

Study objectives

Older people sleep worse than younger people, and sleep affects the secretion of growth hormone and cortisol. The aim of the present study was to quantify the age-dependent changes in the sleep pattern as well as the growth hormone and cortisol secretion in men and investigate possible correlations.

Methods

Polysomnography was performed in the sleep laboratory of 149 healthy men of normal weight between the ages of 16 and 83 years. Blood was drawn from them every 15 to 30 minutes for 24 hours to measure growth hormone and cortisol levels. Shift workers, men who had just returned from a trip with a time difference and competitive athletes were not included in the study.

Results

The duration of sleep decreased with increasing age, with a significant reduction - an average of 27 minutes per decade - not being recorded until around 45 years of age. The proportion of deep non-REM sleep (stages 3 and 4) decreased from almost 19% in the 16 to 25 year olds to around 3.5% in the over 35 year olds and then remained constant into old age. The proportion of REM phases also decreased with age, while the percentage of superficial non-REM sleep (stages 1 and 2) increased slightly. Growth hormone secretion fell from around 600 mg / day in those under 25 to less than 200 mg / day in those over 35. In the course of the day, with increasing age, growth hormone secretion also decreased at night, which is particularly pronounced in young men. Regardless of age, a close correlation was found between growth hormone secretion and the proportion of deep sleep. The daily profile of cortisol levels was similar in younger and older men; only the levels in the hours before midnight were higher in age.

Conclusions

It appears that the deterioration in sleep quality that begins to manifest in men in the third or fourth decade of life is associated with the decrease in growth hormone secretion. In further studies it should be examined whether better sleep in old age promotes growth hormone secretion and thus, for example, can counteract the breakdown of muscle tissue or the decline in performance. (MH)

The large number of individuals examined is positive. A negative factor is that deep sleep (SWS) based on arbitrary EEG amplitude criteria and not the extent of the delta waves was correlated with growth hormone (GH). Reaching the SWS minimum in middle age is an artifact and does not reflect the continuous amplitude reduction of the EEG delta waves. The interpretation of the age-related GH reduction as a pathological GH deficiency is also questionable, as is the assumption that substitution therapy with synthetic GH secretagogues will lead to improved sleep.

Alexander Borbély

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